Automatic mechanical locking device for telescopic jacks



R. E. HAROLD Feb. 15, 1955 AUTOMTIC ,MECHANICAL LOCKING DEVICE FORTELESCOPIC JACKS Filed Feb. 25,. 1951 3 Sheets-Sheet l AUTOMATICMECHANICAL LOCKING DEVICE FOR TELESCCPIC JACKs Filed Feb. 23; 1951 Feb.I5, 195252 R..E. HAROLD 3 Sheets-Sheet 2 Wm NM Nv mm LE Y Feb. 15, 1955R. E. HAROLD K 2,702,024

AUTOMATIC MECHANICAL LOCKING DEVICE FOR TELESCOPIC JACKS Filed Feb. 23,1951 3 Sheets-Sheet 5 lOl Maw/#MM incorporate a lock.

type a locking spring tongue is mounted either on the` United StatesPatent Oy AUTOMATIC MECHANICAL LOCKING DEVICE FOR TELESCOPIC JACKSRobert Edwin Hai-oid, Penkeih, Warrington, England, an

signor to Electro-Hydraulics Limited, Warrington, England, a Britishcompany This invention relates to automatic mechanical locking devicesfor telescopic jacks and is concerned with that type of locking devicewhich comprises a locking means, for example spring claws, a lock sleevethrough or over which the locking means can slide and a spring biasedlock bolt adapted to hold the locking means inl their locking positionto prevent their collapsingor extending as the case may be and slidingback through or over the lock sleeve. Locks of this typev areparticularly useful for uid pressure operated jacks. y

Some of the known locking devices of this type suier from thedisadvantage of having considerable length and when it is desired toincorporate a locking device in a telescopic jack due to thecircumstances governed by the use of the jack its length cannot beincreased to In one known arrangement of this sliding piston assembly oron the cylinder of the jack, and surrounding the piston, or a locksleeve carried by the piston, but here again it will be appreciated thatthe length of the jack has to be increased considerably to include sucha locking arrangement.

It is the object of this invention to provide allocking device of thetype described in a telescopic jack without appreciable increase inlength, thereby overcoming the disadvantages referred to above.

According to the present invention an automatic mechanical lockingdevice of the type described, for use in connection with telescopicjacks, comprises locking means carried by a jack cylinder, co-operatingmeans such as a lock sleeve through which the locking means can slide toeffect engagement with the co-operating means, and a movable lock boltwhich normally lies in the path of the locking means so that when thelocking means approaches the co-operating means, the lock bolt is pushedaway by the locking means, but is capable of returning behind thelocking means when it is moved into the locking position, and then tohold it firmly in engagement with the co-operating means, the saidcooperating means and lock bolt being carried substantially within thejack pistonrod. f

The locking device may include indication means to signify that thelocking device is in the locked or unlocked position.

According to this invention also the locking means and co-operatingmember are duplicated so that the jack can be locked in both theextended or closed position.

Three forms of construction according to this invention arediagrammatically illustrated in the accompanying drawings in whichFigures l and 2 show locking means for the closed (Figure 1) andextended (Figure 2) positions in longitudinal section of one form,whilst Figures 3 and 4 are similar views of an arrangement without lockindication means. Figures 5 and 6 show in fragmentary section twofurther modified forms.

Referring to Figures 1 and 2, the telescopic jack comprises a cylinder 1having fluid connections 2 and 33, an end wall 4 formed withanattacliment lug 3, and a screwed in end nut 34, provided with a bore-through which a hollow piston rod 19 can slide. Fixed to the piston rod19 by a lock sleeve 9 is a piston 21 sliding in the bore of thecylinder. The locking means, in the Vform of a spring tongue or claws 6,is held in the end wall 4 by a shoulder 66 of a spindle 86, which inturn is secured by means of a' nut 5, the part 6 serving for the lockingin the closed position, while similar locking 2,702,024 Patented Feb.15, 1955 rice means 32 serves for the extended position and has a hollowbase 31 provided with external threads for securing onto a shoulder 30in the bore of the piston rod 19. Sliding in the bore of the pitten rod19 are hollow lock 5, bolts 11 and 36 biased into the locking positionby springs 12 and 37 respectively, an aperture 52 being provided in thepiston rod 19 to admit tluid pressure into its bore, l

whilst an eye bolt 68 screwed in the outer end of the piston rod 19 isprovided with a breeze hole 67.

The hollow spindle 86 is provided with slots 46 and 41 and carries, oris made integral with, a lock sleeve 35, and carries on its outer end ascrewed on nut 38 which serves as a rest for the spring 37. In the boreof the hollow spindle 86 slides a solid spindle 40 provided with l5 slot69. Slots 50 and 41, also slots 46 and 69, are capable of registeringtogether. The spindle,40 is secured to the lock bolt 36 by a pinV 42, sothat lthe spindle 40 is restrained to move together with the lock bolt36, but both parts are free to move in relation to the piston rod 20 19and the hollow .spindle 86, as the pin 42 is free to move in therespective slots 41 and 50. interposed between'the hollow spindle 86 andthe solid spindle 40 at their inner ends i s a sleeve 70 free to slidebetween both spindles. A pin 47 is driven into the sleeve 70, while thespring 23 and a washer 48 onto which the spring presses bias the pininto the cylinder. The slots 46 and 69 allow the pin to move in relationto the hollow spindle 86 and solid spindle 40. Onto the cylinder arefixed pins 25 and 44 round which rocker arms 26 and 43 can pivot. Thearm 26 serves as a lock indicator for the'closed position of the jackand the arm 43 as a-flock indicator for the extended position. Glands15, 16, 17, 18, 28, 53, 54, 55, 56, 57, 58, 59, 60, 78, 79 and 80provide seals.

The de vice functions in the following manner: Assuming the Jack to bein the extended position (Figure 2) .and it is desired to retract orclose the jack to the position shown in Figure 1, liuid pressure isadmitted into the Jack cylinder through connection 33 to move-the )ackpiston 21to the left, whereupon uid pressure from the left hand side ofthe piston 2l will be expelled through connection 2. Towards the end ofsuch movement, the spring tongues 6, which are stationary, enter thelock sleeve 9 and are depressed inwardly or collapsed by the sleeve, soas to pass through the sleeve; thereafter the tongues expand, due totheir inherent resiliency. During their last part of the travelthroughthe sleeve 9, the loclt tongues 6 abut the lock bolt 11 and force itaway against the action of its spring 12. Movement of the lock bolt 11against the spring may be assisted by the tiuid back pressure, the otherside of the lock bolt 11 being under in put pressure, due to the iiuidentering the boie of the piston rod 19 by aperture 52. When the springtongues 6 have passed through the lock sleeve 9 and expanded again, thelock bolt 11, due to the action of the spring and possibly assisted bythe uid pressure, forces its way into the spring tongues 6, therebypreventing them from collapsing and sliding back through the lock sleeve9,` so that the locking device is locked to prevent extension of thejack and this lock will hold the ack in the locked closed position untiluid pressure is admitted mtothe cylinder through connection 2 andallowed to be expelled through connection 33. When the lock bolt 11 isforcing its way into the lock tongues 6,

05 in order to lock the jack in its closed position, the lock bolt- 11contacts the pin 47 to move it against the action of its spring 23,thereby in turn` moving the sleeve and the rocker arm 26 about its pivot25, thereby providing an indication for the locking position. When the70 lock is broken, the lock bolt 11 will be carried away by the pistonrod 19 so that the rocker arm 26 can return to its original position,thus indicating that the lock is broken.

Assuming the jack to be in the closed position (Figure l) and it isdesired to extend the jack tothe posi-v tion shown in Figure 2, tluidpressure is admitted into the jack cylinder through connection 2 actingon the left hand side of the piston 21 moving it to the right,

while the uid from the right handk side of the piston 2l is expelledthrough connection 33.

. This duid pressure, entering through connection 2,

. passes through the gaps between the lock tongues 6 and acts on thelock bolt 11 to move it against its spring, so that the spring tongues 6can collapse and the liuid pressure can move the piston 21 to the right,thus extending the jack. As the piston 21 moves to the right, it carriesthe lock sleeve 9 well over the collapsed lock tongues 6 until they canexpand again outside the lock sleeve.

Towards the end of the movement, the spring tongues 32which are carriedby the piston rod 19, pass onto the lock sleeve 35 and are forcedoutwardly or expanded, so as to pass over the sleeve 35. During the lastpart-of their travel over the sleeve 35, the lock tongues 32 abut thelock bolt 36 and force it to the right against the force of its spring,which movement may be assisted by the uid back pressure. When the springtongues 32 have passed over the lock sleeve 35 and return to theirformer position, the lock bolt 36, due to the action of its spring 37,forces its way over the spring tongues 32 thereby preventing them fromexpanding and sliding back over the lock sleeve 35, so that the lockingdevice is locked to prevent closure of the jack and this lock will holdthe jack in the locked extended position until iluid pressure isadmitted into the cylinder through connection 33, passes tthroughaperture 52 into the bore of the piston rod 19, through the slots of thelock tongue 32 and acts on the lock bolt 36 to move it against itsspring 37, so that the spring tongues 32 can expand and the fluidpressure acting on the piston 21l can move it to the left, carrying thelock tongues 32 over the lock sleeve 35 until they can return to theirformer shape after passing over the lock sleeve 35.

When the lock bolt 36 is pushed into the locked position by the locktongues 32, it will carry pin 42 and thus spindle 40 with it, thusrocking the rocker arm 43 about its pivot 44, in order to provide anindication for the locked position on extension. It will be noted thatthe lock bolt 36 is biassed into a different position whether in or outof lock and this different position of the lock bolt 36, and thereforethe associated parts, namely pin 42, spindle v40 and rocker arm 43, willallow remote indication. It will also be noted that spindle 42 andspindle 47 on the other end move in slots so that they do not carryother parts with them.

If no lock indication is desired, the locks may be conveniently in theform as indicated in Figures 3 and 4, in which the same referencenumerals used in Figures l and 2 are used again for similar parts, andas the only essential difference between the two constructions is theomission of the lock indicator means consisting of the rocker arms andtheir associated parts, no detail description is felt to be necessary.

Referring now to Figure of the accompanying drawing, there is providedin the bore of a jack cylinder 100, a slidable piston assembly whichcomprises a hollow piston rod 101 which is internally threaded at itsend for engagement with a lock sleeve 102 which holds in position on thepiston rod a piston 103, the lock sleeve abutting against a washer 104defining one end of the travel of a lock bolt 105 slidably mounted inthe bore of the piston rod 101. The said lock bolt 105 is biassedoutwardly by one end of a spring 106, the other end of which abuts on aWasher 107 which in turn is held thereby on an internal shoulder 108 inthe piston rod. The locking means is in the form of spring tongues'orclaws 109 held in one end wall 110 of the jack cylinder, the tonguesbeing formed on one end of an elongated member 111 which is screwed intothe end wall and retained by a nut 112 andwasher 113. Suitablefluid-tight seals are provided within the jack. The cylinder is providedwith a tluid connection 114 and usual attachment lug The devicefunctions in the following manner: Assuming the iack to be in theextended position and it is desired to retract or close the jack to theposition shown in Figure 5, liuid pressure is admitted to the jackcylinder through a port in the right hand end of the cylinder (notshown), to move the sliding piston assembly into the cylinder andtowards the end of such movement the spring tongues 109 which arestationary, enter the lock sleeve 102 and are depressed inwardly orcollapsed by the sleeve so as to pass through the sleeve; thereafter thetongues expand, due to their inherent resiliency. During the last partof the travel through the sleeve, the lock tongues 109 abut the lockbolt 105 and force this rearwardly against the action of its spring 106.Movement of the lock bolt against this spring may be assisted by thepressure of fluid compressed by the piston 103, and for this purpose thespring tongues adjacent the cylinder end wall are orilced as shown at116. The washer 107 abutting the internal shoulder 108 in the piston rodis preferably apertured as at 117 to allow venting of pressure onmovement of the lock bolt. When the spring tongues 109 have passedthrough the lock sleeve and expand again, the lock bolt 105, due to theaction of its spring, forces its way into the spring tongues, therebypreventing them collapsing and sliding back through the lock sleeve, sothat the locking device is locked to prevent extension of the jack, andthis lock will hold the jack in the locked closed position until uid-pressure is admitted, to the other end of the cylinder throughconnection 114. This uid pressure passes through the orifices 116 in thespring tongues 109 and acts on the lock bolt 105 to move it against itsspring, so that the spring tongues can collapse and allow liuid pressureto act on the sliding piston assembly to extend the jack. As the jackextends the lock sleeve 102 passes over the collapsed lock tongues 109until they can again expand outside the lock sleeve.

When it is desired to obtain an indication at a place remote from thejack, that the jack is lockedI or unlocked, the form shown in Figure 6may be employed. In this figure like reference numerals are used forlike parts in Figure 5. In this arrangement there is provided a spindle118 which passes through the spring tongues 109 and is biassed by aspring 119 into engagement with the lock bolt 105, the other end of thespindle passing out throughI the cylinder end wall 110. The spindle isslidable within the end wall and is adapted to makecontact with one endof a bell crank lever or rocker 120 which is provided on its other endwith a screw and nut arrangement 121, which is capable on movement ofthe rocker of operating a remote indication, for example an electricswitch (not shown). In this arrangement when the spring tongues 109 havepassed through the lock sleeve 102 and the lock bolt 105 has returned toits normal position, due to the action of its spring, the lock boltcontacts the head of the spindle 118 to move it against the action( ofits spring 119, thereby in turn moving the rocker 120 about its pivot122 sov that the screw and nut device 121 will operate the indicationmeans to show that the locking device is in the locked position. When,however, the locking device is moved to the unlocked position asdescribed with reference to Figure 5, the lock bolt 105 is moved awayfrom the spindle 118 which, due to its spring, tends to follow upmovement of the lock bolt, thereby allowing the rocker 120 to move inthe reverse direction to indicate that the locking device is in theunlocked position.

Instead of providing lock spring tongues, the locking means may compriseballs or segments of any known type and, for example, may be of the formdescribed in the specification of our co-pending United Statesapplication Serial No. 173,608, tiled July 13, 1950, now Patent2,685,275 issued August 3, 1954.

I claim:

l. A telescopic jack automatic mechanical locking device comprising ajack cylinder, a hollow piston unit including a piston and piston rodslidable in, said cylinder, locking means comprising a plurality ofspring claws fast with the cylinder, lock cooperating means and a lockbolt, both carried substantially wholly within said piston unit,

said cooperating means comprising a sleeve carried by and projectingwithin said piston rod and forming means for securing said piston tosaid piston rod, said lock bolt being movable vin two directionsrelative to said piston unit and being arranged in the path of saidlocking means, and means biasing said lock bolt for movement in one ofsaid directions towards said locking means upon movement of said pistonunit in such direction, said locking means being movable through saidcooperating means upon movement of said piston unit in said onedirection, and said lock bolt being engageable by said locking meansduring such movement, to be pushed thereby against said biasing means inthe other of said directions relative to said cooperating means, saidlocking means having portions biased into locking engagement with saidcooperating means and said lock bolt being movable by said biasing meansinto contacting relation with said portions of said locking means whensaid portions of said locking means s engage said cooperating means, tomaintain such engag ment.

2. A telescopic jack automatic mechanical locking device comprising ajack cylinder, a hollow piston unit 1ncluding a piston and a piston rodslidable in said cylinder, means for introducing iluid under pressure tosaid cylinder, locking means comprising a plurality of spring claws fastwith the cylinder, lock cooperating means and a lock bolt both carriedsubstantially wholly within said piston unit, said cooperating meanscomprising a sleeve carried by and projeetingwithin said piston rod andforming means for securing said piston to said piston rod, said lockbolt being movable in two directions relative to said piston unit andbeing arranged in the path of said locking means, and means biasing saidlock bolt for movement in one of said directions toward said lockingmeans upon movement of said piston unit in such direction, said lockingmeans being movable through said cooperating means upon movement of saidpiston unit in said one direction, and said lock` bolt having an endarea subject to pressure in said cylinder to move said lock bolt againstsaid biasing means in the other of said directions relative to saidcooperating means, said locking means having portions biased intolocking' engagement with said cooperating means and said lock bolt beingmovable by said biasing means into contacting relation with saidportions of said locking means when said portions of said locking meansengage said cooperating means, to maintain such engagement.

3. A telescopic jack automatic mechanical locking det vice comprising ajack cylinder, a hollow piston unit including a piston and piston rodslidable in said cylinder, locking means comprising a plurality ofspring claws fast with the cylinder, lock cooperating means and a lockbolt, both carried substantially wholly within said piston unit, saidcooperating means comprising a sleeve carried by the `piston rod andinto which said spring clawsare movable,

said lock bolt being movable in two directions relative to said pistonunit and being arranged in the path of said locking means, means biasingsaid lock bolt for movement in one of said directions towards saidlocking means upon movementof said piston unit in such direction, saidlocking means being movable through said cooperating means upon movementof said piston unit in said one direction, and said lock bolt beingengageable by said locking means during such movement, to be pushedthereby against said biasing means in the other of said directionsrelative to said cooperating means, said locking means having portionsbiased into locking engagement with said cooperating means and said lockbolt being movable by said biasing means into contacting relatlon withsaid portions of said locking means when said portions of said locking`means engage said cooperating means, to maintain such engagement, aspindle extending through said claws, a spring biasing said spindle intoengagement with said lock bolt, said cylinder having an end wall throughwhich said spindle is slidable, and a rocker mechanism externally ofsaid cylinder engageable with said spindle to be actuated thereby toform indication means.

4. A telescopic jack automatic mechanical locking device comprising ajack cylinder, a hollow piston unit including a piston and piston rodslidable in said cylinder, locking means carried by said cylinder, lockcooperating means and a lock bolt, both carried substantially whollywithin said piston unit, said lock bolt being movable in two directionsrelative to said piston unit and being arranged in the path of saidlocking means, means biasing said lock bolt for movement in one of saiddirections toward said locking means upon movement of said piston unitin such direction, said locking means being movable through saidcooperating means upon movement of said piston unit in said onedirection, and said lock bolt being engageable by said locking meansduring such movement, to be pushed thereby against said biasing means inthe other of said directions relative to said cooperating means, saidlocking means having portions biased into locking engagement with saidcooperating means and said lock bolt being movable by said biasing meansinto contacting relation with said portions of said locking means whensaid portions of said locking means engage said cooperating means, tomaintain such engagement, a second locking means carried by and arrangedwithin said piston rod, a second cooperating means within said pistonrod fixed against axial movement, a second lock bolt slidable in saidpiston rod, and means biasing said second lock bolt in one direction,said second locking means being engageable with said second cooperatingmeans and with said second lock bolt, and said second lock bolt beingmovable against its biasing means to release said second locking meansfrom said second cooperating means.

5. A telescopic jack automatic mechanical locking device comprising ajack cylinder, a hollow piston unit including a piston and piston rodslidable in said cylinder, means for introducing uid under pressure tosaid cylinder, locking means carried by said cylinder, lock cooperatingmeans and a lock bolt both carried substantially wholly within saidpiston unit, said lock bolt being mov* able in two directions relativeto said piston unit andbeing arranged in the path of said locking means,means biasing saidlock bolt for movement in one of said directionstoward said locking means upon movement of said piston unit in suchdirection, said locking means being movable through said cooperatingmeans upon movement of said piston unit in said one direction, and saidlock bolt having an end area subject to pressure in said cylinder tomove said lock bolt against said biasing means in the other of saiddirections relative to said cooperating means, said locking means havingportions biased into locking engagement with said cooperating means andsaid lock bolt being movable by said biasing means into contactingrelation with said portions of said locking means when said portions ofsaid locking means engage said cooperating means, to maintain suchengagement, a second locking means carried by and arranged within saidpiston rod, a second cooperating means within said piston rod xedagainst axial movement, a second lock bolt slidable in said piston rod,means biasing said second lock bolt in one direction, said secondlocking means being engageable with said seeond cooperating means andwith said second lock bolt, and said second lock bolt being movableagainst its biasing means to release said second locking means from saidsecond cooperating means, and two rockers having mechanicalA connectionwith the respective lock bolts, one rocker indicating the closedposition of the jack and the other indicating the extended position ofthe jack.

References Cited in the le of this patent UNITED STATES PATENTS2,295,961 Meyer Sept. 15, 1942 2,434,828 Ashton Jan. 20, 1948 FOREIGNPATENTS 4362,577 Italy Aug. 30, 1938 493,471 Great Britain Oct. 10, 1938579,294 Great Britain July 30, 1946 615,401 Great Britain Jan. 5, 1949715,461 Germany a Dec. 22, 1941

